Arin Trook, who died Monday in an avalanche near Ashcroft, was the education director at the Aspen Center for Environmental Studies since September 2013.

Arin Trook and his companions on a backcountry hut trip had made several ski runs without incident for two days near the slope where an avalanche tragically claimed Trook’s life on the third day of their outing, according to a report released Monday by the Colorado Avalanche Information Center.

After the two days of safe skiing, Trook and a male companion in his party descended into slightly steeper terrain on the morning of the third day, according to the Colorado Avalanche Information Center report. They had been on slopes near and less than 30 degrees in steepness on Jan. 19 and 20.

“The lack of obvious signs of instability, and numerous safe descents in the lower-angled portions of the slope likely made them feel more comfortable with this particular terrain feature,” said the report prepared by Colorado Avalanche Information Center forecaster Brian Lazar. “On the day of the accident, they descended into steeper terrain, around 35 degrees in steepness, on the skier’s right side of the slope.

“This is only four or five degrees steeper than the terrain they had been skiing,” the report continued. “It may not seem much steeper, but in this case it made a very important difference.”

“It is impossible to know whether this contributed to his burial, or increased his burial depth, but we do know that having things attached to your feet or hands increases the chances you get pulled deeper into the avalanche debris. It is generally safer to use releasable bindings and to not use pole straps while traveling in the backcountry.”Colorado Avalanche Information Center

That difference was enough to result in the skiers triggering a persistent slab avalanche, the type that’s been common throughout the Aspen backcountry this year as new snowfall has accumulated on old, weak layers.

Lazar stressed in his report that Colorado Avalanche Information Center doesn’t investigate avalanches to second-guess decisions, but to note the actions taken by parties in an incident so that other backcountry travelers can learn from the experience.

Multiple laps

The report noted that both men involved in the incident were fathers and husbands of the other group members in the hut. “Their mindset was risk adverse,” Lazar wrote.

The fact they made multiple laps in slightly less steep terrain might have ultimately worked against them.

“It is not uncommon for humans to move into more risky terrain when there is no feedback to suggest things are dangerous,” the report said. “It is hard to recognize this slow drift when you are making a series of decisions throughout a day in the field.”

Trook, 48, was an educator at Aspen Center for Environmental Studies and was regarded as someone with special communication skills. He was beloved within and beyond the conservation organization. A fund has been established to assist his family.

The two couples, both from the Roaring Fork Valley and each with a young child, were scheduled to leave for the Markley Hut on Jan. 18, but they postponed their trip an avalanche warning that day. Avalanche conditions eased and they departed on Jan. 19. The hut is slightly more than 2 miles up the Express Creek Road.

“On Saturday and Sunday the group skied on and around Green Mountain,” the report said. “They typically skied in groups of two, while the other two adults stayed behind at the hut with the young children. The first two days of skiing were enjoyable and uneventful.

“On Saturday, two of the skiers experienced a collapse on a northwest-facing slope on the opposite side of the ridge from the (future) accident site, but otherwise they did not observe any signs of instability,” the report continued. “They skied multiple laps, without incident, on the low-angle, skier’s left — west — margin of the slope that would later avalanche on Monday.”

Hundreds of feet across

Trook and the other male in the party left the hut at around 6:30 a.m. on Jan. 21. They skinned along a ridgeline on the top of Green Mountain to get some early-morning views, then started skiing back on the ridgeline before deciding to wrap around a rock outcrop on the opposite side of the slope they had been skiing the two days prior.

Trook’s companion skied a short way through dense trees and stopped to watch Trook’s descent. Trook skied 150 to 200 vertical feet when he triggered the avalanche.

“The avalanche quickly propagated several hundred feet across the slope and the crown released approximately 150 to 200 feet above (Trook), near where Skier 1 was standing,” the report said. “Skier 1 yelled ‘avalanche’ but wasn’t sure if (Trook) heard him. Skier 1 lost sight of (Trook) as the debris began flowing down the slope to where the terrain was a little steeper.”

Lowest beacon reading

The men carried avalanche beacons and the signal led Trook’s companion to a small stand of trees. Probing with a pole was difficult so he started digging at the point of the lowest beacon reading.

The companion estimated he had exposed Trook’s airway about 10 minutes after the avalanche. He found him not breathing and without a pulse. He extricated him from the snow and performed CPR for between 5 and 10 minutes before heading to the cabin one-third of a mile away to get help. Two adults went back to continue resuscitation efforts.

Meanwhile, a backcountry guide who was with a client passed by the hut and learned of the accident from the adult remaining at the hut. The guide was also a member of Mountain Rescue Aspen and called in the accident via radio. The guide and the client went to the accident scene and the four people continued with CPR for about 30 minutes without success.

11,150 elevation

The avalanche was about 400 feet wide and ran about 400 vertical feet, a distance of about 600 linear feet the report said. It was at an elevation of 11,150 feet on a northeast aspect. The avalanche danger was rated as considerable, level 3 of 5, near and above treeline and moderate, level 2, below treeline on the fatal day. CAIC had issued a Special Avalanche Advisory that was in effect through Jan. 21. It advised that avalanche conditions remained dangerous even though an avalanche warning had expired.

The CAIC report urged backcountry travelers to use trip plans and checklists for outings and rule out potentially dangerous terrain before going out. “Stick to the plan in the field, no matter how enticing that terrain feature might look,” the report said.

Lazar noted that Trook was using non-releasable telemark bindings. One ski came off in the avalanche. One remained.

“It is impossible to know whether this contributed to his burial, or increased his burial depth, but we do know that having things attached to your feet or hands increases the chances you get pulled deeper into the avalanche debris,” the report said. “It is generally safer to use releasable bindings and to not use pole straps while traveling in the backcountry.”

The graduates of Vail Mountain School’s class of 2019 will be off to far-flung destinations next fall, set to enter college in one of 16 different states or explore the world on a gap year. One grad is even attending college in Canada.